Objectives: Elementary school classrooms that meet the acoustic requirements for near-optimum speech recognition are extremely scarce. Poor classroom acoustics may become a barrier to speech understanding as children enter school. The purpose of this study was threefold: 1) to quantify the extent to which reverberation, lexical difficulty, and presentation mode affect speech recognition in noise, 2) to examine to what extent auditory-visual (AV) integration assists with the recognition of speech in noisy and reverberant environments typical of elementary school classrooms, 3) to understand the relationship between developing mechanisms of multisensory integration and the concurrently developing linguistic and cognitive abilities.
Design: Twenty-seven typically developing children and 9 young adults participated. Participants repeated short sentences reproduced by 10 speakers on a 30” HDTV and/or over loudspeakers located around the listener in a simulated classroom environment. Signal-to-noise ratio (SNR) for 70 (SNR70) and 30 (SNR30) percent correct performance were measured using an adaptive tracking procedure. Auditory-visual integration was assessed via the SNR difference between AV and auditory-only (AO) conditions, labeled speech-reading benefit (SRB). Linguistic and cognitive aptitude was assessed using the NIH-Toolbox: Cognition Battery (NIH-TB: CB).
Results: Children required more favorable SNRs for equivalent performance when compared to adults. Participants benefited from the reduction in lexical difficulty, and in most cases the reduction in reverberation time. Reverberation affected children’s speech recognition in AO condition and adults in AV condition. At SNR30, SRB was greater than that at SNR70. Adults showed marginally significant increase in AV integration relative to children. Adults also showed increase in SRB for lexically hard versus easy words, at high level of reverberation. Development of linguistic and cognitive aptitude accounts for approximately 35% of the variance in AV integration, with crystalized and fluid cognition composite scores identified as strongest predictors.
Conclusions: The results of this study add to the body of evidence in support of children requiring more favorable SNRs to perform the same speech recognition tasks as adults in simulated listening environments akin to school classrooms. Our findings shed light on the development of AV integration for speech recognition in noise and reverberation during the school years, and provide insight into the balance of cognitive and linguistic underpinnings necessary for AV integration of degraded speech.